Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 51.653
Filtrar
1.
Artigo em Chinês | MEDLINE | ID: mdl-34218569

RESUMO

Objective: A gas chromatography-tandem mass spectrometry detection method for benzene and its metabolites was established to provide methodological support and theoretical basis for the study of benzene toxicity mechanism. Methods: In August 2019 to March 2020, the animal model of containing high concentration of benzene by inhalation of poison through the respiratory tract of mice was established, taken the blood of mice after dyeing the poison, and the HLB solid phase extraction method was used to extract and purify the samples. The gas chromatography-tandem mass spectrometry detection method was used to qualitative and quantitative analysis of the target substances. After separated by HP-17MS capillary chromatographic column, the compounds were ionized with EI ion source, mass spectrometry detection was carried out by selective ion scanning method (SIM) , and quantification was carried out by external standard curve method. Results: Benzene and its metabolites (phenol, catechol, hydroquinone and m-trihydroxybenzene) in blood could be effectively separated and quasi deterministic and quantitative by this method. The regression equations and correlation coefficients of this method for detecting benzene and its metabolites were: benzene: y=3252.1x+1540, r=0.9993; phenol: y=2046.5x+1423, r=0.9991; catechol: y=1853.9x+945, r=0.9993; hydroquinone: y=1891.5x+840, r=0.9992; m-trihydroxybenzene: y=1052.4x+655, r=0.9991. The detection limits for benzene, phenol, catechol, hydroquinone and m-trihydroxybenzene were 0.03, 0.03, 0.05, 0.05 and 0.10 µg/g, respectively. And the lower limits of quantification were 0.10, 0.10, 0.15, 0.15 and 0.30 µg/g, respectively. The intra-assay precision interval was 2.64%-10.06%, the inter-assay precision interval was 1.37%-10.17%, and the spike recovery rate was 89.8%-102.3%. This method could be used to quantitatively detect benzene, phenol, catechol, hydroquinone and m-trihydroxybenzene in the blood of benzene-infected mice. Conclusion: Solid phase extraction-gas chromatography-mass spectrometry can be used for qualitative and quantitative detection of benzene and its metabolites (phenol, catechol, hydroquinone and m-trihydroxybenzene) accurately.


Assuntos
Benzeno , Espectrometria de Massas em Tandem , Animais , Biomarcadores , Cromatografia Gasosa-Espectrometria de Massas , Camundongos , Extração em Fase Sólida
2.
Sensors (Basel) ; 21(11)2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34200440

RESUMO

Volatile organic compounds (VOCs) are chemicals emitted by various groups, such as foods, bacteria, and plants. While there are specific pathways and biological features significantly related to such VOCs, detection of these is achieved mostly by human odor testing or high-end methods such as gas chromatography-mass spectrometry that can analyze the gaseous component. However, odor characterization can be quite helpful in the rapid classification of some samples in sufficient concentrations. Lower-cost metal-oxide gas sensors have the potential to allow the same type of detection with less training required. Here, we report a portable, battery-powered electronic nose system that utilizes multiple metal-oxide gas sensors and machine learning algorithms to detect and classify VOCs. An in-house circuit was designed with ten metal-oxide sensors and voltage dividers; an STM32 microcontroller was used for data acquisition with 12-bit analog-to-digital conversion. For classification of target samples, a supervised machine learning algorithm such as support vector machine (SVM) was applied to classify the VOCs based on the measurement results. The coefficient of variation (standard deviation divided by mean) of 8 of the 10 sensors stayed below 10%, indicating the excellent repeatability of these sensors. As a proof of concept, four different types of wine samples and three different oil samples were classified, and the training model reported 100% and 98% accuracy based on the confusion matrix analysis, respectively. When the trained model was challenged against new sets of data, sensitivity and specificity of 98.5% and 98.6% were achieved for the wine test and 96.3% and 93.3% for the oil test, respectively, when the SVM classifier was used. These results suggest that the metal-oxide sensors are suitable for usage in food authentication applications.


Assuntos
Nariz Eletrônico , Compostos Orgânicos Voláteis , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Aprendizado de Máquina , Odorantes/análise , Compostos Orgânicos Voláteis/análise
3.
Talanta ; 233: 122542, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215045

RESUMO

The tailor-prepare solid phase microextraction (SPME) coatings with stable and excellent properties to effectively extract analytes from sample matrix still remains a challenge. Herein, a nitrogen doped graphitic carbon networks (NG-CNTW) coated fiber was fabricated by direct carbonization of nanosized ZIF-67 crystals (nano-ZIF-67) that grown on stainless steel wire. The NG-CNTW coated fiber coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was applied for enrichment and determination of pyrethroids. The NG-CNTW coating exhibited high surface area and hierarchical porous structures that facilitate diffusion and accessibility of target molecules. Simultaneously, the nitrogen doped and highly graphitic structures endow the coating with high adsorption affinity for aromatic compounds. Under optimum conditions, the SPME-GC-MS/MS method presented wide range of linearity performance (0.08-200.0 ng g-1), low limits of detection (0.02-0.5 ng g-1) and good repeatability (RSD < 9.6%) for 8 kinds of pyrethroids. Furthermore, the proposed method was successfully applied in the determination of pyrethroids in grape and cauliflower samples, as the results were in the range of 3.16-15.06 ng g-1and 2.08-9.29 ng g-1, respectively. This work not only provides a new method by fabricating carbon nanomaterial coatings in situ derived from MOFs, but also shows great potential of MOFs derivative materials in environmental analysis field.


Assuntos
Grafite , Praguicidas , Piretrinas , Poluentes Químicos da Água , Carbono , Cromatografia Gasosa-Espectrometria de Massas , Nitrogênio , Praguicidas/análise , Microextração em Fase Sólida , Espectrometria de Massas em Tandem , Poluentes Químicos da Água/análise
4.
Talanta ; 233: 122583, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215075

RESUMO

Carbon nanospheres (CNSs) were derived hydrothermally from biomass (orange peels) and decorated by manganese dioxide (MnO2) nanosheets. The MnO2/CNSs nanocomposite was intercalated into polypyrrole (PPy) during flow-through in-situ electropolymerization of pyrrole on the surface of the inner wall of a stainless-steel needle to prepare an inside-needle capillary adsorption trap (INCAT) device. The surface morphology, thermogravimetric behavior, sorption characteristics, and structure of the MnO2/CNSs@PPy nanocomposite were characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray analysis (EDX), nitrogen physisorption by the Brunauer-Emmett-Teller (BET) method, dynamic light scattering (DLS) size distribution, and Fourier-transform infrared spectrometry (FT-IR). The INCAT device was coupled with GC-FID and applied for dynamic headspace analysis of linear alkyl benzenes (LABs) in wastewater samples. The effective experimental variables on the extraction efficiency was optimized using a central composite design (CCD) based on response surface methodology (RSM). Under the optimal conditions, the limits of detection (LODs) were in the range of 0.5-1.0 ng mL-1. The calibration plots were linear over the range of 0.01-10 µg mL-1. The relative standard deviations (RSDs%) for intra-day, inter-day, and inter-INCAT precision were calculated 5.3-8.3%, 9.4-13.5%, and 13.6-16.9%, respectively. The developed technique was employed successfully for the analysis of LABs in water and wastewater samples with average recovery values ranging from 92 to 109%. A single INCAT device was used more than 90 times without significant change in its extraction capability.


Assuntos
Nanosferas , Polímeros , Adsorção , Biomassa , Carbono , Cromatografia Gasosa-Espectrometria de Massas , Compostos de Manganês , Óxidos , Pirróis , Espectroscopia de Infravermelho com Transformada de Fourier
5.
Talanta ; 233: 122495, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215113

RESUMO

Traditional non-targeted chemometric workflows for gas chromatography-mass spectrometry (GC-MS) data rely on using supervised methods, which requires a priori knowledge of sample class membership. Herein, we propose a simple, unsupervised chemometric workflow known as variance rank initiated-unsupervised sample indexing (VRI-USI). VRI-USI discovers analyte peaks exhibiting high relative variance across all samples, followed by k-means clustering on the individual peaks. Based upon how the samples cluster for a given peak, a sample index assignment is provided. Using a probabilistic argument, if the same sample index assignment appears for several discovered peaks, then this outcome strongly suggests that the samples are properly classified by that particular sample index assignment. Thus, relevant chemical differences between the samples have been discovered in an unsupervised fashion. The VRI-USI workflow is demonstrated on three, increasingly difficult datasets: simulations, yeast metabolomics, and human cancer metabolomics. For simulated GC-MS datasets, VRI-USI discovered 85-90% of analytes modeled to vary between sample classes. Nineteen out of 53 peaks in the peak table developed for the yeast metabolome dataset had the same sample index assignments, indicating that those indices are most likely due to class-distinguishing chemical differences. A t-test revealed that 22 out of 53 peaks were statistically significant (p < 0.05) when using those sample index assignments. Likewise, for the human cancer metabolomics study, VRI-USI discovered 25 analytes that were statistically different (p < 0.05) using the sample index assignments determined to highlight meaningful sample-based differences. For all datasets, the sample index assignments that were deduced from VRI-USI were the correct class-based difference when using prior knowledge. VRI-USI holds promise as an exploratory data analysis workflow for studies in which analysts do not readily have a priori class information or want to uncover the underlying nature of their dataset.


Assuntos
Metaboloma , Metabolômica , Análise por Conglomerados , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Fluxo de Trabalho
6.
Environ Monit Assess ; 193(8): 470, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34226978

RESUMO

The high patronage of herbal medicinal products in Ghana for the treatment of diverse disease conditions raises concerns about patient safety, given that much of the raw materials for production are obtained from the wild or farmlands potentially exposed to varied agrochemical residues. Therefore, the work sought to investigate the contamination of herbal medicinal products with pesticide residues and assess the potential risk posed to patients. As a result, validated gas chromatography with mass spectrometry as a detector was used to determine forty-two pesticides in thirty herbal medicinal products. The performance parameters of the method such as linearity, accuracy, and precision were found as acceptable. Pesticide residues such as chlorpyrifos and/or bifenthrin were found in 4/30 herbal medicinal products. Specifically, 3/30 herbal medicinal products contained only one pesticide, while 1/30 was contaminated with both pesticide residues. The levels of pesticide residue contamination ranged between 2.5 and 5.0 µg/kg. The acute hazard quotient and chronic hazard quotient for the two pesticide residues were evaluated and ranged between 0.21 and 0.92% and between 8.21 × 10-4 and 5.88 × 10-3%. The detected pesticide residue levels are below the maximum residue limit values, which may not cause acute and chronic health risks due to intake of the selected herbal medicinal product. Nevertheless, patient safety and potential public health risk can be reduced by regular monitoring, and regulation of pesticide residue levels in herbal medicinal products.


Assuntos
Resíduos de Praguicidas , Monitoramento Ambiental , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas , Gana , Humanos , Resíduos de Praguicidas/análise , Medição de Risco
7.
Molecules ; 26(12)2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34207862

RESUMO

Olive leaves are a highly available by-product from table olive and olive oil production. They are nowadays strongly valuable for their major bioactive compounds and their beneficial effects. To determine the differences between two Croatian domestic (Lastovka, Oblica) and two introduced (Leccino, Frantoio) cultivars, physical and chemical analysis of olive leaves were performed: surface area, color variability, total phenolic amounts, and essential oil volatile profiles were analyzed at three harvest periods. All cultivars greatly differed in surface area, with cv. Lastovka being the smallest. Color variability resulted in an overall decrease in darkness and amounts of green and yellow that could be attributed to a decrease in photosynthetic demand and chlorophyll content. The highest amount of total phenolic content occurred in the summer months, followed by a reduction until October. Essential oils volatiles were determined by GC-MS and showed great diversity not only amongst cultivars but also between harvest periods, with overall 45 compounds identified. Principal component analysis distinguished domestic cultivar Oblica from the other observed cultivars, mainly due to its essential oil volatile fingerprint. Compounds that differentiated cv. Oblica were aldehydes ((E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, decanal), ketones ((E)-ß-damascone, dihydrodehydro-ß-ionone), sesquiterpenes (cyclosativene, α-copaene, α-muurolene) and saturated hydrocarbons (tetradecane, hexadecane). Essential oil volatile fingerprint attributed the highest to the biodiversity of domestic cv. Oblica through all three harvest periods.


Assuntos
Clorofila/química , Óleos Voláteis/química , Olea/química , Fenóis/química , Folhas de Planta/química , Compostos Orgânicos Voláteis/análise , Cromatografia Gasosa-Espectrometria de Massas , Olea/classificação , Tocoferóis/química
8.
Se Pu ; 39(8): 816-826, 2021 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-34212582

RESUMO

Antibiotics have been overused in recent years because of their remarkable curative effect, but this has led to considerable environmental pollution. Therefore, the development of approaches aimed at the effective detection and control of the antibiotics is vital for protecting the environment and human health. Many conventional strategies (such as high-performance liquid chromatography (HPLC), gas chromatography (GC), high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)) are currently in use for the detection of antibiotics. These strategies have aroused a great deal of interest because of their outstanding features of high efficiency and speed, good reproducibility, automation, etc. However, various problems such as tedious sample pretreatment, low detection sensitivity, and high cost must be overcome for the effective detection of antibiotics in environmental samples. Consequently, it is of great significance to improve the detection sensitivity of antibiotics. The development of new materials combined with the existing detection technology has great potential to improve the detection results for antibiotics. Carbon dots (CDs) are a new class of nanomaterials with particle sizes in the range of 0-10 nm. In addition, CDs have desirable properties such as small particle effect, excellent electrical properties, unique optical properties, and good biocompatibility. Hence, they have been widely utilized for the detection of antibiotics in environmental samples. In this review, the application of CDs combined with sensors and chromatographic technology for the detection of antibiotics in the last five years are summarized. The development prospects of CD-based materials and their application to the analysis and detection of antibiotics are presented. In this review, many new sensors (CDs combined with molecularly imprinted polymer sensors, aptamer sensors, electrochemiluminescence sensors, fluorescence sensors, and electrochemical sensors) combined with CD-based materials and their use in the detection of antibiotics are summarized. Furthermore, advanced analysis methods such as ratiometric sensor and array sensor methods are reviewed. The novel analysis methods provide a new direction toward the detection of antibiotics by CDs combined with a sensor. Moreover, CD-based chromatographic stationary phases for the separation of antibiotics are also summarized in this manuscript. It is reported that the detection sensitivity for antibiotics can be greatly improved by the combination of CDs and a sensor. Nevertheless, a literature survey reveals that the detection of antibiotics in complex environmental samples is confronted with numerous challenges, including the fabrication of highly sensitive sensors in combination with CDs. Furthermore, the development of novel high-performance materials is of imperative. In addition, it is important to develop new methods for effective data processing. The separation of antibiotics with CDs as the chromatographic stationary phases is in the preliminary stage, and the separation mechanism remains to be clarified. In conclusion, there are still many problems to be overcome when using CDs as novel materials for the detection of antibiotics in environmental samples. Nowadays, CD-based materials are being intensively studied, and various analytical detection technologies are being rapidly developed. In the future, CD-based materials are expected to play an important role in the detection of antibiotics and other environmental pollutants.


Assuntos
Antibacterianos , Carbono , Pontos Quânticos , Antibacterianos/análise , Cromatografia Gasosa-Espectrometria de Massas , Nanoestruturas , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem
9.
Se Pu ; 39(8): 827-834, 2021 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-34212583

RESUMO

With rapid urbanization, increasing amounts of chemicals are being used in our daily life. Emerging organic contaminants are a large class of chemicals that are widely detected in the environment. They include pharmaceuticals and personal care products, pesticides, perfluorinated compounds, and endocrine-disrupting compounds. Recently, many countries have reported the occurrence of emerging organic contaminants. In addition, emerging organic contaminants are frequently detected in various environmental samples, including river and lake water samples. Despite their low concentrations in the environment, emerging organic contaminants are potential risks to humans and wildlife. Because they could lead to endocrine disrupting effects and the occurrence of resistance genes. Thus, the detection of emerging organic contaminants in the environment is imperative for ecological systems and human health. The recent development of analytical techniques has led to the identification of more emerging organic contaminants in the environment. At present, the commonly used chromatographic separation techniques include liquid chromatography and gas chromatography. For the identification and quantitation of emerging organic contaminants, chromatography is usually combined with spectroscopy or mass spectrometry. The concentrations of emerging organic contaminants are not sufficiently high to be detected directly, and the matrix is complex in environmental samples. Emerging organic contaminants also have diverse properties. Thus, environmental samples must be pretreated before detection. Pretreatment includes the concentration and purification of the environmental samples. The commonly used pretreatment methods are ultrasound-assisted extraction, QuEChERS, liquid-liquid extraction, and solid-phase extraction. With the development of pretreatment methods, solid-phase microextraction and stirred-bar adsorption extraction have also become popular. These sample pretreatment methods have many advantages such as good efficiency and effectivity for recycling target compounds. Hence, they are widely used. However, these methods are time-consuming, in addition to requiring expensive consumables and large amounts of organic solvents. Lyophilization is a technique used for product dehydration, preservation, and storage in the agricultural and food industries. It is also occasionally used to simplify the extraction procedure for drug residue analysis. There are three stages of lyophilization: freezing, primary drying, and secondary drying. Lyophilization has many advantages when used for pretreatment, namely, operational simplicity, less consumables, less sample volume, prolonged storage, and minimal sample loss. Lyophilization is thus an alternative method for the pretreatment of emerging organic contaminants in environmental samples. Recently, lyophilization has been applied to the pretreatment of emerging organic contaminants in environmental water samples. In general, a few steps were included during sample analysis. First, the samples were pretreated and frozen before the primary drying stage. After lyophilization, the analytes were extracted using a small amount of organic solvent and dried with nitrogen. Consequently, the elution was reconstructed and detected after dryness and filtration. Many groups of emerging organic contaminants could be recovered, including antibiotics, pesticides, and endocrine-disrupting compounds. The lyophilization could be automated, so that minimal manual intervention was required. By adopting lyophilization, good recoveries and accuracies were achieved. A few cleanup processes were conducted, and a small amount of organic solvent was consumed. Thus, lyophilization is a highly prospective pretreatment method for monitoring emerging organic contaminants, and can be extended to a diverse range of these contaminants. For large-scale and high-frequency sampling campaigns, cheap and convenient pretreatment is urgently needed. In this study, typical emerging organic contaminants are described, along with the universal types of such contaminants and the principles of lyophilization. The application of lyophilization to the detection of emerging organic contaminants in the environment is also introduced. The future of lyophilization is discussed, which provides a reference for emerging contaminant detection in environmental samples.


Assuntos
Liofilização , Poluentes Químicos da Água , Cromatografia Líquida , Cromatografia Gasosa-Espectrometria de Massas , Estudos Prospectivos , Extração em Fase Sólida , Poluentes Químicos da Água/análise
10.
Bioresour Technol ; 337: 125476, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34320756

RESUMO

This paper proposed a novel method for modification of dolomite (Do) using the leaching solution derived from the spent ternary LIBs. During catalytic pyrolysis of biomass, the modified Do showed a good performance on both reducing the activation energy and upgrading the volatile products. The apparent activation energy was decreased from 201 to 180 kJ/mol for the cellulose pyrolysis, and it was decreased from 80 to 75 kJ/mol for the lignin pyrolysis. The cellulose pyrolysis with the modified Do could significantly promote the conversion of anhydrosugars into small-molecule components (e.g., ketones). Meanwhile, the Do modified by transition-metal (e.g., Mn, Co, Ni) oxides had a high catalytic activity in cracking phenols (main tar precursors) to hydrocarbons (e.g., aromatics) during the lignin pyrolysis. The modified Do inhibited the production of phenols (from 50% to 5.8%) and enhanced the production of hydrocarbons (from 0.6% to 30.3%).


Assuntos
Lítio , Pirólise , Biomassa , Carbonato de Cálcio , Catálise , Cromatografia Gasosa-Espectrometria de Massas , Magnésio
11.
Molecules ; 26(12)2021 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-34208377

RESUMO

Cerebrospinal fluid is a key biological fluid for the investigation of new potential biomarkers of central nervous system diseases. Gas chromatography coupled to mass-selective detectors can be used for this investigation at the stages of metabolic profiling and method development. Different sample preparation conditions, including extraction and derivatization, can be applied for the analysis of the most of low-molecular-weight compounds of the cerebrospinal fluid, including metabolites of tryptophan, arachidonic acid, glucose; amino, polyunsaturated fatty and other organic acids; neuroactive steroids; drugs; and toxic metabolites. The literature data analysis revealed the absence of fully validated methods for cerebrospinal fluid analysis, and it presents opportunities for scientists to develop and validate analytical protocols using modern sample preparation techniques, such as microextraction by packed sorbent, dispersive liquid-liquid microextraction, and other potentially applicable techniques.


Assuntos
Doenças do Sistema Nervoso Central/líquido cefalorraquidiano , Biomarcadores/líquido cefalorraquidiano , Doenças do Sistema Nervoso Central/diagnóstico , Doenças do Sistema Nervoso Central/metabolismo , Líquido Cefalorraquidiano/química , Líquido Cefalorraquidiano/metabolismo , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Metaboloma
12.
Nutrients ; 13(6)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208504

RESUMO

The soybean allergen Gly m 4 is known to cause severe allergic reactions including anaphylaxis, unlike other Bet v 1 homologues, which induce mainly local allergic reactions. In the present study, we aimed to investigate whether the food Bet v 1 homologue Gly m 4 can be a sensitizer of the immune system. Susceptibility to gastrointestinal digestion was assessed in vitro. Transport through intestinal epithelium was estimated using the Caco-2 monolayer. Cytokine response of different immunocompetent cells was evaluated by using Caco-2/Immune cells co-culture model. Absolute levels of 48 cytokines were measured by multiplex xMAP technology. It was shown that Gly m 4 can cross the epithelial barrier with a moderate rate and then induce production of IL-4 by mature dendritic cells in vitro. Although Gly m 4 was shown to be susceptible to gastrointestinal enzymes, some of its proteolytic fragments can selectively cross the epithelial barrier and induce production of Th2-polarizing IL-5, IL-10, and IL-13, which may point at the presence of the T-cell epitope among the crossed fragments. Our current data indicate that Gly m 4 can potentially be a sensitizer of the immune system, and intercommunication between immunocompetent and epithelial cells may play a key role in the sensitization process.


Assuntos
Antígenos de Plantas/farmacologia , Hipersensibilidade Alimentar/terapia , Imunização/métodos , Antígenos de Plantas/imunologia , Células CACO-2/efeitos dos fármacos , Células CACO-2/imunologia , Quimiocinas/metabolismo , Técnicas de Cocultura , Citocinas/metabolismo , Escherichia coli/metabolismo , Hipersensibilidade Alimentar/imunologia , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Modelos Biológicos , Organismos Geneticamente Modificados , Células THP-1/efeitos dos fármacos , Células THP-1/imunologia
13.
Molecules ; 26(12)2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-34203867

RESUMO

In recent years, there has been a growing interest in studying and exploring the potential health benefits of foods, mainly from vegetables and fruits from regular intake. The presence of secondary metabolites, namely polyphenols, carotenoids and terpenes, in certain food matrices seems to contribute to their functional properties, expressed through an increased prevention in the development of certain chronic diseases, namely coronary heart diseases, neurodegenerative diseases, cancer and diabetes. However, some foods' volatile secondary metabolites also present important bioactive properties, although this is a poorly scientifically explored field. In this context, and in order to explore the potential bioactivity of volatile metabolites in different vegetables and fruits from regular consumption, the volatile composition was established using a green extraction technique, solid phase microextraction in headspace mode (HS-SPME), combined with gas chromatography tandem mass spectrometry (GC-MS). A total of 320 volatile metabolites, comprising 51 terpenic compounds, 45 organosulfur compounds, 31 aldehydes, 37 esters, 29 ketones, 28 alcohols, 23 furanic compounds, 22 hydrocarbons, 19 benzene compounds, 13 nitrogenous compounds, 9 carboxylic acids, 7 ethers, 4 halogenated compounds and 3 naphthalene derivatives, were positively identified. Each investigated fruit and vegetable showed a specific volatile metabolomic profile. The obtained results revealed that terpenic compounds, to which are associated antimicrobial, antioxidant, and anticancer activities, are the most predominant chemical family in beetroot (61%), orange carrot (58%) and white carrot (61%), while organosulfur compounds (antiviral activity) are dominant in onion, garlic and watercress. Broccoli and spinach are essentially constituted by alcohols and aldehydes (enzyme-inhibition and antimicrobial properties), while fruits from the Solanaceae family are characterized by esters in tamarillo and aldehydes in tomato.


Assuntos
Frutas/química , Verduras/química , Compostos Orgânicos Voláteis/química , Álcoois/análise , Aldeídos/análise , Ésteres/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Cetonas/análise , Metabolômica/métodos , Microextração em Fase Sólida/métodos , Terpenos/química , Compostos Orgânicos Voláteis/análise
14.
Molecules ; 26(12)2021 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-34204654

RESUMO

Vanilla (Vanilla planifolia) is a precious natural flavoring that is commonly used throughout the world. In the past, all vanilla used in Taiwan was imported; however, recent breakthroughs in cultivation and processing technology have allowed Taiwan to produce its own supply of vanilla. In this study, headspace solid-phase microextraction (HS-SPME) combined with GC-FID and GC-MS was used to analyze the volatile components of vanilla from different origins produced in Taiwan under different cultivation and processing conditions. The results of our study revealed that when comparing different harvest maturities, the composition diversity and total volatile content were both higher when the pods were matured for more than 38 weeks. When comparing different killing conditions, we observed that the highest vanillin percentage was present after vanilla pods were killed three times in 65 °C treatments for 1 min each. From the experiment examining the addition of different strains, the PCA results revealed that the volatiles of vanilla that was processed with Dekkera bruxellensis and Bacillus subtilis was clearly distinguished from which obtained by processing with the other strains. Vanilla processed with B. subtilis contained 2-ethyl-1-hexanol, and this was not detected in other vanillas. Finally, when comparing the vanillin percentage from seven different regions in Taiwan, vanilla percentage from Taitung and Taoyuan Longtan were the highest.


Assuntos
Vanilla/química , Vanilla/metabolismo , Compostos Orgânicos Voláteis/química , Agricultura/métodos , Benzaldeídos/química , Benzaldeídos/isolamento & purificação , Cromatografia Gasosa/métodos , Aromatizantes/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Extratos Vegetais/análise , Microextração em Fase Sólida/métodos , Taiwan , Compostos Orgânicos Voláteis/análise
15.
Molecules ; 26(12)2021 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-34204728

RESUMO

This study aimed at an experimental design of response surface methodology (RSM) in the optimization of the dominant volatile fraction of Greek thyme honey using solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). For this purpose, a multiple response optimization was employed using desirability functions, which demand a search for optimal conditions for a set of responses simultaneously. A test set of eighty thyme honey samples were analyzed under the optimum conditions for validation of the proposed model. The optimized combination of isolation conditions was the temperature (60 °C), equilibration time (15 min), extraction time (30 min), magnetic stirrer speed (700 rpm), sample volume (6 mL), water: honey ratio (1:3 v/w) with total desirability over 0.50. It was found that the magnetic stirrer speed, which has not been evaluated before, had a positive effect, especially in combination with other factors. The above-developed methodology proved to be effective in the optimization of isolation of specific volatile compounds from a difficult matrix, like honey. This study could be a good basis for the development of novel RSM for other monofloral honey samples.


Assuntos
Mel/análise , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Grécia , Thymus (Planta)/metabolismo
16.
Molecules ; 26(12)2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34207244

RESUMO

Fast diagnostic results using breath analysis are an anticipated possibility for disease diagnosis or general health screenings. Tests that do not require sending specimens to medical laboratories possess capabilities to speed patient diagnosis and protect both patient and healthcare staff from unnecessary prolonged exposure. The objective of this work was to develop testing procedures on an initial healthy subject cohort in Hawaii to act as a range-finding pilot study for characterizing the baseline of exhaled breath prior to further research. Using comprehensive two-dimensional gas chromatography (GC×GC), this study analyzed exhaled breath from a healthy adult population in Hawaii to profile the range of different volatile organic compounds (VOCs) and survey Hawaii-specific differences. The most consistently reported compounds in the breath profile of individuals were acetic acid, dimethoxymethane, benzoic acid methyl ester, and n-hexane. In comparison to other breathprinting studies, the list of compounds discovered was representative of control cohorts. This must be considered when implementing proposed breath diagnostics in new locations with increased interpersonal variation due to diversity. Further studies on larger numbers of subjects over longer periods of time will provide additional foundational data on baseline breath VOC profiles of control populations for comparison to disease-positive cohorts.


Assuntos
Expiração/fisiologia , Compostos Orgânicos Voláteis/química , Adolescente , Adulto , Testes Respiratórios/métodos , Feminino , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hawaii , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Adulto Jovem
17.
Molecules ; 26(12)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208560

RESUMO

Pectis elongata is found in the northern and northeastern regions of Brazil. It is considered a lemongrass due to its citric scent. The remarkable citral content and the wide antimicrobial properties and bioactive features of this terpene make this essential oil (EO) eligible for several industrial purposes, especially in cosmetics and phytotherapics. However, to address the problems regarding citral solubility, nano-emulsification is considered a promising strategy thanks to its improved dispersability. Thus, in this paper we propose a low-energy approach for the development of citral-based nano-emulsions prepared with P. elongata EO. The plant was hydrodistillated to produce the EO, which was characterized with a gas chromatograph coupled to mass spectrometry. The nano-emulsion prepared by a non-heated water titrating (low-energy) method was composed of 5% (w/w) EO, 5% (w/w) non-ionic surfactants and 90% (w/w) deionized water and was analyzed by dynamic light scattering. Levels of citral of around 90% (neral:geranial-4:5) were detected in the EO and no major alteration in the ratio of citral was observed after the nano-emulsification. The nano-emulsion was stable until the 14th day (size around 115 nm and polydispersity index around 0.2) and no major alteration in droplet size was observed within 30 days of storage. Understanding the droplet size distribution as a function of time and correlating it to concepts of compositional ripening, as opposing forces to the conventional Ostwald ripening destabilization mechanism, may open interesting approaches for further industrial application of novel, low-energy, ecofriendly approaches to high citral essential oil-based nano-emulsions based on lemongrass plants.


Assuntos
Monoterpenos Acíclicos/isolamento & purificação , Emulsões/química , Óleos Voláteis/isolamento & purificação , Monoterpenos Acíclicos/química , Brasil , Cymbopogon/química , Cromatografia Gasosa-Espectrometria de Massas , Monoterpenos/química , Óleos Voláteis/química , Extratos Vegetais/isolamento & purificação , Tensoativos/química , Água/química
18.
Molecules ; 26(12)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208757

RESUMO

BACKGROUND: Pesticide residues are a threat to the health of the global population, not only to farmers, applicators, and other pesticide professionals. Humans are exposed through various routes such as food, skin, and inhalation. This study summarizes the different methods to assess and/or estimate human exposure to pesticide residues of the global population. METHODS: A systematic search was carried out on Scopus and web of science databases of studies on human exposure to pesticide residues since 2019. RESULTS: The methods to estimate human health risk can be categorized as direct (determining the exposure through specific biomarkers in human matrices) or indirect (determining the levels in the environment and food and estimating the occurrence). The role that analytical techniques play was analyzed. In both cases, the application of generic solvent extraction and solid-phase extraction (SPE) clean-up, followed by liquid or gas chromatography coupled to mass spectrometry, is decisive. Advances within the analytical techniques have played an unquestionable role. CONCLUSIONS: All these studies have contributed to an important advance in the knowledge of analytical techniques for the detection of pesticide levels and the subsequent assessment of nonoccupational human exposure.


Assuntos
Exposição Ambiental/análise , Resíduos de Praguicidas/efeitos adversos , Praguicidas/efeitos adversos , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Indicadores Básicos de Saúde , Humanos , Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Praguicidas/análise , Extração em Fase Sólida/métodos , Solventes/química
19.
Molecules ; 26(11)2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34199338

RESUMO

The fecal metabolome in early life has seldom been studied. We investigated its evolution in pre-term babies during their first weeks of life. Multiple (n = 152) stool samples were studied from 51 babies, all <32 weeks gestation. Volatile organic compounds (VOCs) were analyzed by headspace solid phase microextraction gas chromatography mass spectrometry. Data were interpreted using Automated Mass Spectral Deconvolution System (AMDIS) with the National Institute of Standards and Technology (NIST) reference library. Statistical analysis was based on linear mixed modelling, the number of VOCs increased over time; a rise was mainly observed between day 5 and day 10. The shift at day 5 was associated with products of branched-chain fatty acids. Prior to this, the metabolome was dominated by aldehydes and acetic acid. Caesarean delivery showed a modest association with molecules of fungal origin. This study shows how the metabolome changes in early life in pre-term babies. The shift in the metabolome 5 days after delivery coincides with the establishment of enteral feeding and the transition from meconium to feces. Great diversity of metabolites was associated with being fed greater volumes of milk.


Assuntos
Fezes/química , Metabolômica/métodos , Compostos Orgânicos Voláteis/análise , Cesárea/estatística & dados numéricos , Nutrição Enteral , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Idade Gestacional , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Modelos Lineares , Gravidez , Microextração em Fase Sólida
20.
Molecules ; 26(11)2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34199618

RESUMO

This study determined the antimicrobial and antioxidant activity of lemongrass (LO), thyme (TO), and oregano (OO) essential oils and ethanolic extracts of pomegranate peel (PPE) and grape pomace (GPE) as candidate ingredients for edible coatings. Antifungal effects against Botrytis cinerea and Penicillium spp. were tested using paper disc and well diffusion methods. Radical scavenging activity (RSA) was evaluated using 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid assays. Gas chromatography-mass spectrometry analysis identified limonene (16.59%), α-citral (27.45%), ß-citral (27.43%), thymol (33.31%), paracymene (43.26%), 1,8-cineole (17.53%), and trans-caryphellene (60.84%) as major compounds of the essential oils. From both paper disc and well diffusion methods, LO recorded the widest zone of inhibition against tested microbes (B. cinerea and Penicillium spp.). The minimum inhibitory concentrations of LO against B. cinerea and Penicillium spp., were 15 µL/mL and 30 µL/mL, respectively. The highest (69.95%) and lowest (1.64%) RSA at 1 mg/mL were recorded for PPE and OO. Application of sodium alginate and chitosan-based coatings formulated with LO (15 or 30 µL/mL) completely inhibited spore germination and reduced the decay severity of 'Wonderful' pomegranate. Lemongrass oil proved to be a potential antifungal agent for edible coatings developed to extend shelf life of 'Wonderful' pomegranate.


Assuntos
Anti-Infecciosos/farmacologia , Antioxidantes/farmacologia , Cymbopogon/química , Óleos Voláteis/farmacologia , Origanum/química , Thymus (Planta)/química , Anti-Infecciosos/química , Antioxidantes/química , Botrytis/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Testes de Sensibilidade Microbiana , Óleos Voláteis/química , Penicillium/efeitos dos fármacos , Óleos Vegetais/química , Óleos Vegetais/farmacologia , Esporos Fúngicos/efeitos dos fármacos , Terpenos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...